You may be able to move your Documents and Settings folder onto a different drive. That way you can preserve all the unique data in there the next time you wiupe your installation drive. Otherwise, Thunderbird will be the least of your worries. Or you can leave it where it is and make sure to always back up that folder hierarchy.

I thought perhaps TweakUI could do the move, but it only handles some of the special sub-folders for the current user account. Likely another tool out there or a registry hack and manual file/folder move.

When programs didn't support multi-user environments, people complained. Now that they do... People complain. Some programs offer settings so you can override the behaviour whichever way you want. Haven't done a final install/switch to Thunderbird yet. I will for both XP and Mac OS though. (For Mac OS I've already moved my /Users/ hierarchy off the root partition to somewhere else for this same reason.)

Bruno